Honor killing has nothing to do with Islam. The Quran does not condone honor killings and honor killings
There is more to Islam than the Quran.
Islam's "honor" has been defended with murder since early on.
1. March 624: Al-Nadr bin al-Harith
Before Muhammad’s Hijrah (Emigration from Mecca to Medina in 622), he used to sit in the assembly and invite the Meccans to Allah, citing the Quran and warning them of God’s punishment for mocking his prophets. Al-Nadr would then follow him and speak about heroes and kings of Persia, saying, "By God, Muhammad cannot tell a better story than I, and his talk is only of old fables which he has copied as I have." Al-Nadr is referring to legends and opaque histories about Arabs of long ago and possibly to Bible stories about such figures as Noah, Abraham, Moses, and Jesus, which Muhammad told, but according to his own inaccurate versions. On other days al-Nadr would interrupt Muhammad until the prophet silenced him. In reply to al-Nadir’s harassment, it is possible (scholars sometimes have difficulties matching up Quranic verses with historical events) that Allah sent down these verses to Muhammad concerning him or certainly other mockers in Mecca, according to the account of Ibn Abbas, Muhammad’s cousin, who is considered a reliable transmitter of traditions:
25:6 Say [Prophet], "It was sent down by Him who knows the secrets of the heavens and earth. He is all forgiving and merciful." (MAS Abdel Haleem, The Qur’an, Oxford UP, 2004)
83:13 ... [W]hen Our revelations are recited to him, he says, "Ancient fables!" 14 No indeed! Their hearts are encrusted with what they have done. 15 No indeed! On that day they will be screened off from their Lord, 16 they will burn in Hell, 17 and they will be told, "This is what you call a lie." (Haleem)
Muhammad did not take revenge on him—not yet—even though the verses in Sura 83 promise a dismal eternal future for mockers. Muhammad’s revenge was not long coming. It was al-Nadir’s bad fortune to join Mecca’s army, riding north to protect their caravan, which Muhammad attacked at the Battle of Badr in AD 624. The story-telling polytheist was captured, and on Muhammad’s return journey back to Medina, Ali, Muhammad’s son-in-law, at Muhammad’s order, beheaded him, instead of getting some possible ransom money. He was one of two prisoners who were executed and not allowed to be ransomed by their clans—all because they wrote poems and told stories critiquing Muhammad.
Source: Ibn Ishaq, The Life of Muhammad, trans. A. Guillaume, (Oxford UP, 1955, 2004), pp. 136 (Arabic pages 191-92); 163 / 236; 181 / 262; 308 / 458. Reputable historians today consider Ibn Ishaq to be a good source of early Islam, though they may disagree on his chronology and miraculous elements.